The present invention relates generally to a method for managing a system for supplying an onboard network of a vehicle with electrical energy.
FIG. 1 illustrates a known system for supplying an onboard network of a vehicle with electrical energy. The system 1 comprises a generator 3 (for example, an alternator, a starter-alternator or a DC/DC converter (DC/DC)), an electrical energy storage device 5 such as a 12V battery, an onboard network 7 including all the electrical and electronic components of the vehicle, a set 9 including a switch K and a DC/DC converter 11, and an additional electrical energy storage device 13 which is connected to the set 9 and the DC/DC convertor 11.
The operation of the system 1 can be divided into two phases:
Phase 1: Switch K (MOS, electromechanical relay, diode) is closed. The generator 3 is driven by a vehicle heat engine and generates electric energy. This electrical energy allows recharging battery 5, powering all the electrical and electronic components of the onboard network 7 and charging the additional storage device 13 via the DC/DC integrated converter 11 integrated in set 9.
Phase 2: Switch K is open. Generator 3 and battery 5 are isolated from other organs by switch K. Generator 3 can be driven and produce electrical energy to recharge the battery 5 or be stopped and therefore the battery 5 imposes its voltage to the terminals of generator 3. The DC/DC converter 11 of set 9 and 13 allow the additional storage device to provide electrical power to the onboard network 7 while ensuring satisfactory voltage for the onboard network needs (e.g. 13.5V). Then when the additional storage device 13 no longer has enough energy, the set 9 integrated DC/DC converter 11 stops working, switch K is closed and the generator 3 and the battery 5 become the main energy source for the onboard network.
These two phases are repeated periodically.
However, during the transition from phase 2 to phase 1, stopping the DC/DC converter 11 of the set 9 can generate a voltage drop seen by the onboard network 7 causing, for example, a decrease of intensity of the lights or a reset some vehicle computers. This is illustrated in FIGS. 2A and 2B.
For example, let us assume that the onboard network represents a power consumption of 50A.
Switch K is open, thus isolating the generator and the battery 5 and the DC/DC converter 11 of the additional storage device 13 and the onboard network.
When the generator 3 is stopped, the voltage of the battery 5 is imposed on the generator terminals 3. The DC/DC converter 11 and the additional storage device 13 provide 50A to the onboard network 7 while regulating the voltage across the board network (e.g. 13.5V).
When the DC/DC converter 11 stops operating, the switch K is closed, and the consumption of the onboard network 7 is therefore directly imposed on the generator 3 and battery 5. The generator 3 and battery 5 see this 50A consumption imposed as a high current draw. Battery 5 temporarily provides this energy requirement to the network 7 before the generator 3 resumes out and becomes the main energy source. During the supply of power from the battery 5 following the stop of the DC/DC converter 11, a voltage drop may be imposed on the onboard network 7 (FIG. 2B).
This voltage drop could deprive a safe function of the vehicle of energy.